It is now well established that the plasma membrane is composed of various types of microdomains containing unique sets of proteins and lipids. Among these, cholesterol- and saturated-lipid-enriched microdomains known as lipid rafts have been the subject of much interest and debate across several disciplines of biology. We and others demonstrated that lipid rafts play important roles in HIV-1 assembly and entry. We have explored the possibility that cholesterol-depleting and cholesterol-binding compounds inhibit HIV-1 replication. Our efforts have focused on amphotericin B methyl ester (AME), a cholesterol-binding polyene fungal antibiotic. We have observed that AME inhibits both assembly/release and virus entry and have identified a novel mechanism of escape from this compound, involving cleavage of the cytoplasmic tail of gp41 by the viral protease (PR). [Corresponds to Freed Project 3 in the April 2007 site visit report of the HIV Drug Resistance Program]